A trial against six environmental activists has been suddenly dropped after an
undercover police officer switched allegiance and offered to testify on
their behalf.

The campaigners had been accused of conspiring to shut down a power station, but the trial collapsed after Pc Mark Kennedy, who had infiltrated the group, indicated he would give evidence to support them in court, it has been reported.

Prosecutors dropped the case, which was due to start on Monday, after learning that Mr Kennedy had offered to help the defence, according to BBC Newsnight.

The charges related to an alleged plan by the activists to try to shut down the Ratcliffe-on-Soar coal-fired power station in Nottingham in 2009 to protest against global warming.

Under the alias Mark Stone, Mr Kennedy led a second life as an environmental campaigner in Nottingham.

The undercover agent had become a key member of the group since 2000 until his secret was discovered by protesters last October.